I have a general question that is rather open-ended (i.e. "depends on platform, application type, etc.") but I am looking for general guidelines as an answer.
When is it preferable to design an application for continuous operation (100% uptime) vs. scheduled daily shutdown/restart?
Obviously, web apps need to be up all the time, so assume for this question that we are discussing an internal enterprise application, such as an accounting system, or a B2B system that is only used actively during weekday business hours.
Arguments I've heard for each are as follows:
Pro 100% Uptime: "once you get an application running, it's better to keep it up, because there's a chance it won't restart when you shut it down."
Pro daily restarts: "an application that is up continuously for 3 years might one day go down, and nobody will know how to bring it back online."
Other considerations are memory growth, performance, need for maintenance, etc. This is a programming issue because the choice you make can affect your technical design. For example, you don't need to code certain batch jobs and clear state daily if you know the application will be shutdown/restarted daily.
Thoughts?
The arguments you state both for and against 100% uptime are foolish arguments, in my opinion. If you're worried about the application not restarting when it is shutdown then you have larger issues than uptime concerns. Likewise, if you feel that nobody will know how to bring it back online after a prolonged period of uptime you have training and documentation issues.
The reality is that you should always design an application to be efficient when it comes to memory consumption and performance. Generally, by doing this you end up with an application that can sucessfully survive as a long running process or one that restarts frequently. Keep in mind that your typical computer system is rebooted periodically anyway due to OS updates, etc.
Unless you have requirements and service level agreements that guarantee 100% uptime, this isn't usually something you have to be overly concerned about as long as you design an application efficiently.